Greenhouse Gas Emissions Gap Means More Work Ahead

Jerald Schnoor is attending the Paris climate meeting on assignment for C&EN. He is a professor and codirector of the Center for Global & Regional Environmental Research at the University of Iowa and former editor-in-chief of Environmental Science & Technology.﻿﻿

The so-called emissions gap is the difference between countries’ pledged INDCs (brown and green lines; shading indicates uncertainty ranges) and the annual emissions maximum necessary to limit warming to 2 °C above preindustrial levels (blue line). Without further action to restrain emissions, the gap grows in later years. Unlike unconditional INDCs, “conditional INDCs” are pledges made by some developing countries that are dependent on international assistance to be carried out. Both kinds of INDCs reduce emissions compared with the current policy trajectory (yellow line).

Credit: UNEP

MIND THE GAP

The so-called emissions gap is the difference between countries’ pledged INDCs (brown and green lines; shading indicates uncertainty ranges) and the annual emissions maximum necessary to limit warming to 2 °C above preindustrial levels (blue line). Without further action to restrain emissions, the gap grows in later years. Unlike unconditional INDCs, “conditional INDCs” are pledges made by some developing countries that are dependent on international assistance to be carried out. Both kinds of INDCs reduce emissions compared with the current policy trajectory (yellow line).

Credit: UNEP

Cautious optimism predominates in Paris this week at the United Nations climate conference, the talks aiming to prevent global warming of 2 °C or more above preindustrial levels. Government representatives are cautiously optimistic because the Paris meeting has been framed strategically, unlike the last major climate conference, held in Copenhagen in 2009. For starters, most national pledges were made before the Paris meeting commenced, so everyone knows what to expect as an outcome. Nearly 190 countries, representing the source of some 98% of the world’s global emissions, already have ponied up commitments to cutting global greenhouse gas emissions by 2025 or 2030.

Officially called intended nationally determined contributions or INDCs, these are voluntary “bottom up” pledges unlike the mandates in the Kyoto protocol, a 1997 climate change accord. The Kyoto protocol prescribed precisely how much industrialized nations were to cut emissions, and the formal treaty was considered legally enforceable on those who ratified it. As a consequence, the U.S. never participated.

Because INDCs are voluntary, the agreement expected to come out of Paris will likely not require formal ratification by the U.S. Senate. This feature guarantees greater acceptance of the pact and bodes well for its long-term success.

The Paris meeting and the pledging process have garnered the participation of almost all countries. Developing countries are expected to have plans to manage their greenhouse gas emissions, forests, and land use and to adapt to an already-changing climate—just like industrialized nations. Of course, richer countries face peer pressure to cut emissions to a greater extent than low-income countries that might need cheap fossil fuels in the short term to improve living standards. After all, high-income countries have emitted most of the greenhouse gases stemming from human activities that are present in the atmosphere today and are responsible for the great majority of the warming that has already taken place. And high-income countries have the financial means to transition their economies from fossil fuels to renewables in a timely manner.

But before the backslapping begins for the outcome of the Paris meeting, we must mind the emissions gap: Countries’ pledged emissions reductions are not nearly enough to solve the problem of climate change. In fact, they are barely enough to curtail the current 2% annual growth rate in worldwide greenhouse gas emissions. So how much is needed?

The truth is we need to double or triple the cuts pledged so far. First, we need to level off emissions within the next five to 10 years and then drastically slash greenhouse gas emissions by 50–70% as of 2050. Given current pledges, the gap between global emissions and levels necessary to limit warming to less than 2 °C would widen from about an equivalent of 5 gigatons of carbon dioxide per year in 2020 to the equivalent of 12–14 Gt of CO2 annually by 2030. That is why the work in Paris is just beginning. Governments should meet every five years or so to update their pledges and ratchet down emissions further.

Even if all countries abide by their current pledges, we are not off the hook yet. It will require concerted effort and negotiations for decades to come. Climate change is the defining environmental problem of this century.